The changing emphases of the National Science Education Standards (NSES) have spurred many school districts to reinvent their science programs. New curricula development by National Science Foundation-funded programs have been at the core of some districts' comprehensive plans to reform science education through changing emphases in content, teaching, and assessment. This chapter features two districts—Lemon Grove, California and Charleston, South Carolina—that have developed and followed a comprehensive plan for the reform of science education through changes in curriculum, assessment, and instructional practices.